Satellite tag contributed to the death of a 20-year-old orca, experts say

When a 20-year-old killer whale named Nigel was found dead floating off Vancouver Island at the end of March, experts expressed immediate concern about the sharp barbs that remained embedded in the whale’s dorsal fin. (See Water Ways, April 14.)

Nigel, L-95, on the day he was darted with a satellite tag. Photo: Northwest Fisheries Science Center
Nigel, L-95, on the day he was darted with a satellite tag. He was later found dead.
Photo: Northwest Fisheries Science Center

This type of barb is commonly used to attach satellite transmitters to all sorts of whales and dolphins, allowing the animals to be tracked over long distances. The satellite tags are designed to fall off completely — but that did not happen for Nigel, designated L-95.

As the result of an investigation by the National Oceanic and Atmospheric Administration, we now know that the barbs helped to introduce a dangerous fungus into Nigel’s body. The fungus appears to have spread to his lungs and other organs, ultimately contributing to his death.

“After a thorough necropsy and investigation, including an expert review of findings, there was sufficient evidence to implicate the tag attachment site as a source of fungal infection to the whale,” states a report by an expert panel (PDF 209 kb). “This fungal infection contributed to illness in the whale and played a contributory role in its death.”

After Nigel was found dead near Nootka Island, NOAA suspended the satellite-tracking program. As a result of these latest findings, the agency announced today that it will continue to prohibit satellite tagging, at least until new standards can be developed through the International Whaling Commission.

After that, any further tagging would require a new review under the Endangered Species Act. That’s because the Southern Residents — the orcas that frequent Puget Sound — are listed as an endangered species.

The tagging program has provided much information about where the whales go during winter months when they leave Puget Sound and travel up and down the coast. That information is expected to help NOAA Fisheries develop a new “critical habitat” designation for the Southern Residents. Critical habitat in coastal areas might provide the whales with protected areas where they could hunt for chinook salmon, their primary prey.

For now, NOAA may need to use methods other than satellite tagging to keep track of the whales during winter, said Richard Merrick, chief scientist for NOAA Fisheries. Experts are reviewing the existing data to see if they have enough information for expanding critical habitat outside of Puget Sound.

A total of eight Southern Residents have been tagged using a similar dart system since tagging began in 2012, according to a report from Brad Hanson (PDF 972 kb) of NOAA’s Northwest Fisheries Science Center. Nigel was the last, and all the other whales are alive and have shed their darts, although one whale did retain a dart for a while.

The fungus that contributed to Nigel’s death has been found in the surface waters off Vancouver Island, experts say, and the attached tag provides an entry point for infection. A couple of factors may have made things worse for the orca. First, the tag was dropped during handling and may have become contaminated with seawater. Although it was sterilized with alcohol, protocols for tag deployment call for the use of bleach as well.

It was a “human error,” said Merrick, adding that the NOAA scientists involved are “dismayed” that any of their actions could have contributed to the orca’s death.

The tag also went into a spot on the dorsal fin lower than recommended. Although other whales have not had problems with this location, the concern is the proximity to large blood vessels that could allow the fungal organism to more easily enter the bloodstream.

The final necropsy report (PDF 365 kb) provides evidence that Nigel may have had some problems with his immune system, and this particular fungus is known to attack people who are immune-compromised. I have written about the added risks of disease among killer whales because of their exposure to toxic chemicals. You might want to check out my series in the Encyclopedia of Puget Sound.

Because Nigel’s carcass was severely decomposed when it was found, the actual cause of death may never be known. But contributing factors are many.

Ken Balcomb, longtime orca researcher for the Center for Whale Research, had warned about the risks involved with using sharp prongs that penetrate the skin. See “Orca tagging raises questions about research” from Dec. 8, 2010, and “Orca researchers divided over use of satellite tags” from Dec. 28, 2010.

Reached by phone today, Ken told me that he has given his best information to government researchers through the years — not only about the risks of tagging but about other issues as well.

“I get no communication back,” he said. “They just ignore it.”

His greatest concerns today are focused on the lack of wild salmon to feed the whales, he said. The high death rate and the low birth rate in recent years largely results from a lack of food, which compounds other problems that the orcas are facing. While nine new orca calves since the end of 2014 is encouraging, he said, the 82 Southern Residents are not in good shape as a population.

“They do have to eat,” Ken said. “This population requires a certain quantity of fish, and they are not getting it. Recovery (of the orcas) is not happening, and it won’t happen until the recovery of natural fish populations happens.”

The removal of dams on the Snake River would help increase the wild chinook population, Ken said, but better management of all life stages of salmon is essential. That means better coordination between the U.S. and Canada, he added.

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